An organic light-emitting device is a device that includes an anode, a cathode, and an organic compound layer interposed between the anode and the cathode. Holes and electrons injected from the respective electrodes of the organic light-emitting device are recombined in the organic compound layer to generate excitons and light is emitted as the excitons return to their ground state. The organic light-emitting device is also called an organic electroluminescent device or organic EL device. Recent years have seen remarkable advances in the field of organic light-emitting devices. Organic light-emitting devices offer low driving voltage, various emission wavelengths, rapid response, and small thickness and are light-weight.
Phosphorescence-emitting devices are a type of device that includes an organic compound layer containing a phosphorescence-emitting material, with triplet excitons contributing to emission. Creation of novel organic compounds has been actively pursued to provide high-performance phosphorescence-emitting devices.
PTL 1 discloses a compound 1 used as a host material of a phosphorescence-emitting device. The compound 1 is a xanthone derivative having carbazolyl groups.

Since the excited triplet (T1) energy of this compound is low, this material is not suitable as a host material of an emission layer of a blue or green phosphorescence-emitting device or as a material for forming a carrier transport layer.